Self-Resetting Double-Piston Hydraulic Drive for Engine Valve Trains
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Solution Overview
Problem
Existing engine valve trains face challenges in integrating a compact hydraulic drive device that can coexist with automatic valve clearance adjustment, while additional reset devices complicate the system and reduce reliability.
Innovation Solution
A self-resetting single-valve double-piston hydraulic drive device for overhead cam engines, featuring a rocker arm assembly with a primary driving piston and a secondary driving piston connected through a driving oil passage, which automatically resets and eliminates the need for additional hydraulic clearance adjustment devices, reducing system complexity and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional engine brake system is integrated into the valve train, then braking function is achieved, but system complexity increases due to additional reset devices
Solution Approach 1:
The patent combines the engine drive function and automatic valve clearance adjustment function into a single hydraulic drive device. The primary driving piston and secondary driving piston are integrated within the existing valve train structure, eliminating the need for separate reset devices while achieving both braking and valve clearance adjustment functions.
Solution Approach 2:
The hydraulic drive device performs multiple functions: it provides engine braking through the primary driving piston and simultaneously performs automatic valve clearance adjustment through the secondary driving piston. This multi-functionality reduces the need for additional specialized components.
2Volume of moving object
If a compact hydraulic drive device is integrated into the valve train, then space efficiency improves, but accommodating both drive and clearance adjustment functions becomes difficult
Solution Approach 1:
The secondary driving piston is nested within the valve bridge assembly, while the primary driving piston is positioned in the rocker arm. The hydraulic passage connects these nested components, allowing both functions to coexist in a compact arrangement without interfering with each other's operation.
Solution Approach 2:
The patent utilizes the vertical dimension by positioning the primary driving piston in the rocker arm (upper dimension) and the secondary driving piston in the valve bridge (lower dimension). This spatial arrangement allows both functions to operate independently in different dimensional zones while maintaining compact overall volume.
3Ease of operation
If additional reset devices are added to the valve train, then valve reset function is achieved, but maintenance requirements increase
Solution Approach 1:
The secondary driving piston automatically resets the valve by utilizing the hydraulic pressure differential created during engine operation. The system self-regulates valve clearance without requiring external reset devices or manual intervention, reducing maintenance complexity while maintaining the valve reset function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a compact, reliable, and low-maintenance engine drive system with reduced noise, impact, and wear, allowing for automatic valve clearance adjustment without additional devices, enhancing operational durability and simplicity.
Implementation Method 1
a hydraulic passage, wherein the hydraulic passage connects the primary driving piston with the secondary driving piston
Implementation Method 2
an elastic component, wherein the elastic component is located in the valve bridge assembly and the elastic component pushes the secondary driving piston
Data Source
AI summary
A self-resetting single-valve double-piston hydraulic drive device and method for an overhead cam engine is disclosed. A primary driving piston and a secondary driving piston are respectively provided on a rocker arm body and a valve bridge body. The secondary driving piston is connected to an exhaust valve. When the drive control valve opens, the primary driving piston and the secondary driving piston realize a hydraulic linkage, during a drive lift, the secondary driving piston opens the exhaust valve. At the beginning of the positive-power lift, the secondary driving piston is automatically reset. When the control valve is closed, during the drive lift of an integrated cam, the primary driving piston absorbs the drive lift of an integrated cam assembly, the rocker arm body and the bridge body do not move, and the drive lift of the integrated cam is not transmitted to the exhaust valve.